1、 Technical Overview

This technology takes the design of a new water system from source control to process reduction, with a small amount of terminal treatment as the research concept. A detailed investigation and analysis were conducted on the bottleneck problem of wastewater discharge in coal chemical enterprises and specific engineering cases of "zero discharge" of wastewater in specific regions. Drawing on engineering experience in salt chemical, sugar making, fruit juice, seawater desalination, and other fields, a preliminary technical plan and research work for "zero discharge" of energy chemical wastewater were determined through industry technology intersection and system integration innovation. In the absence of engineering precedents in the industry, the entire zero discharge and resource utilization engineering system process plan consisting of five subsystems (particle removal, scaling ion removal, organic pollutant removal, three-stage separation and concentration, and crystallization separation) and twelve operating units was determined.

2、 Technical advantages

(1) Coagulation and sedimentation technology

By studying the reaction sequence and speed of the coagulation and sedimentation system, an enhanced coagulation and sedimentation process was developed, and the types of chemicals added and operating parameters of the high-density coagulation and sedimentation tank were determined. The effect of coagulation and sedimentation on hardness removal was improved from the industry wide range of 30-50mg/L to 3-5mg/L.

(2) High pH multi-stage reverse osmosis technology

This technology can enable the reverse osmosis process to operate continuously under high pH conditions, reducing the pollution of silicon and organic matter on the reverse osmosis membrane. Although it requires high precision in operation control, its process flow is short, and the back end can be combined with an amorphous seed evaporation crystallization device. The recovery rate of the unit device can be maintained above 90%. The estimated operating cost (electricity consumption+chemical consumption) is 8 yuan/m3.

(3) No reverse flow shutdown technology

Through extensive research and experiments, the method of replacing concentrated water on the concentrated water side with produced water while the high-pressure pump is still in operation has been adopted to eliminate osmotic pressure and fundamentally solve the corresponding problems caused by reverse flow. And by adjusting and controlling the time of each production and discharge valve, the concentrated water side is continuously diluted until the concentration on both sides approaches before shutting down, fundamentally avoiding the existence of reverse flow. Compared with other chemical wastewater treatment industries, the service life of the membrane device can be extended from 1 year to 3 years.

(4) Salt separation technology

The nanofiltration bi-directional separation technology not only achieves single-stage nanofiltration treatment of two-component inorganic salt solutions, increasing the purity of sodium chloride to over 98.5%, but also has greater advantages in operating costs compared to other industry salt separation methods. The use of salt separation technology to turn wastewater salt into qualified industrial products greatly reduces environmental and social problems in local industrial production areas.

3、 Applicable scope

Mainly suitable for areas with abundant coal resources but scarce water resources in the northwest, where the water quality has the characteristics of high salinity and high organic pollutants. A new technology for industrial water cycle treatment needs to be developed to improve conversion efficiency and resource utilization, reduce energy and water consumption, and achieve coordinated development of economic and environmental benefits. This technology can be used as a complete set of equipment for deep treatment and reuse of chemical wastewater.